Method of installing an interior by-pass liner

ABSTRACT

Interior by-pass for underground gas service line is installed from building basement without need for excavation, and has a tightenable adapter attached on each end of the by-pass tubing to connect and seal the tubing to the interior periphery of the service line. Each adapter provides a pair of spaced-apart expanded sealing gaskets between the tubing and the service line, and a gas-leakage passage extending from the interior of the tubular adapter to the exterior spacing between the adapter gasket pair. Temporary gas-tight plugs are provided at respective locations between each leakage passage and the adjacent end of the by-pass tubing, and compressed natural gas test-pressure is applied within the tubing. Via both of the referred to leakage passages, the test pressure is exerted against all of the gasket seals to confirm gas-tightness thereof. Techniques are described for installing each adapter and the by-pass tubing, working only from the service end of the line, including installation of the service end adapter prior to the blind end adapter; the use of temporary gas-inflation bags to permit installation of the by-pass in the face of service gas flow; and structures on each adapter to fully expand the innermost gasket of each pair before the outermost gasket is expanded.

This is a division of application Ser. No. 204,629, filed Nov. 6, 1980,now U.S. Pat. No. 4,377,945, which is a continuation of application Ser.No. 955,990, filed Oct. 30, 1978, abandoned.

FIELD OF INVENTION

This invention relates to techniques for rehabilitating lengths of leakyfluid-conducting conduits which are relatively inaccessible, such asunderground utility service lines which conduct natural gas from astreet main into the basement of a house or building. More particularly,the invention relates to methods and apparatus for installing a smallerdiameter interior by-pass conduit within and along the length of anexisting larger but deteriorated conduit to conduct the fluid normallyconducted by the latter, thus to avoid any leak points.

Although the invention may have other uses, it was made during anattempt to devise a more effective way to install and test such aninterior by-pass conduit within an underground gas service line withoutneed for any ground excavation, and it will therefore be described inconnection with such use.

BACKGROUND OF THE INVENTION AND THE PRIOR ART

A conventional buried distribution network of pipes for conductingnatural or produced gas from a public utility throughout a city and intohomes or buildings for heating purposes includes large diameter gasmains extending beneath and along the city streets, from each of whichmany smaller diameter gas service lines extend laterally, each fordelivering the gas into a house or other building. In low pressuresystems for delivering the gas at a pressure of about 6"-water column(0.25 p.s.i.g.) each such service line is usually made of from11/4"-diameter to 2"-diameter or larger pipe, whereas in higher pressuresystems (e.g., 48"-water column, or 2.0 p.s.i.g.) the diameter of theservice line may be 1/2", or 3/4", or larger. The service line extendssome 25 to 50 feet underground from a tee connection on the topcenterline of the gas main to and through the building wall, and intothe basement. Ordinarily there is no manhole located at the main teeconnection, so that the tee as well as the service time itself isinaccessible without excavation, being buried several feet under thepaved street. The steel pipe of which the service line is made passesbeneath any sidewalk, lawn, garden and the like, all being ground areaswhich are not intended to be disturbed. A curb valve, normally of thegate type and accessible by way of a street level valve box, may or maynot be located within the service line to shut off gas glow whendesired.

When because of breakage or corrosion one or more leaks develop in sucha service line, a common repair technique is to install an internalconduit, usually made of metal or plastic tubing, to carry the gas pastthe leak points. The installation is usually made working mainly fromthe basement or service end of the line, and extends all the way to themain. Some street excavation has been required to reach the teeconnection at the gas main, both to shut off the flow of gas from themain and to open the service line to make the required interiorconnection between the liner tubing and the service line adjacent to themain, thus to avoid replacement of the service line as would entaildigging and trenching along much if not all of its length.

A common technique for connecting a plastic liner tubing at the streetend of a conventional steel service line involves removal of a shortsection of the service line adjacent to the main, and substitution of aprefabricated steel pipe adapter section to which a length of theplastic liner pipe has already been permanently joined, as by acompression coupling formed integrally with the adapter section. In thisprocedure, after the required street excavation to locate the gas maintee connection, and after the flow of gas from the main has been stoppedand the required length of the existing service line has been removed,the plastic liner pipe is fed through the service line from the buildingbasement and its foward end is connected to the adapter section. Thelatter is then connected to the tee-fitting on the main. Having thusconnected the liner conduit at the street end, the service end of theliner pipe is connected to the interior of the service line at the pointwhere it projects into the basement through the building wall, and avariety of service head adapters and techniques are known for doing sowithout any excavation adjacent to the building. Of course, beforeinstalling the liner the interior of the service line must be cleaned ofdirt and scale by reaming as necessary, including possible reamingthrough any curb valve in the line.

In general, such interior by-pass installations requiring excavation atthe gas main are known, and are shown for example in U.S. Pat. Nos.2,268,263 (Newell et al.) and 2,546,348 (Schuman). Similar installationswhich are intended to be made working solely from the basement orservice head end of the service line, thus requiring no streetexcavation at all, are disclosed for example in U.S. Pat. Nos. 2,731,041(Mueller et al.); 2,756,779 (Tratzik et al.); and 2,829,675 (Mueller etal.), although in these patents only relatively short lengths of theliner pipe are described as extending only a short distance outwardlyfrom the building wall rather than over the entire distance to the gasmain as contemplated by the present invention. All of the foregoing aswell as other patents, such as U.S. Pat. Nos. 2,487,939 (Norton);2,641,491 (Mueller et al.); and 3,244,438, describe a variety ofadapters for connecting and hermetically sealing the liner tubing to theservice head end of the service line in such internal by-pass systems.

However, known by-pass arrangements which extend all the way from thebuilding to the main are not generally believed to be effectivelyinstalled without any steet excavation, and are therefore considered tobe very costly in terms of the time, inconvenience and expense involvedin such street excavation and in replacing the ground and its cover toits original condition. Regarding known types of interior by-passinstallations which do not require street excavation, it is believedthat, while they may be effective working with short lengths, theyprobably cannot be reliably installed where the length of by-pass tubingextends from the building to any location beyond the curb valve, whichmust be shut or cut off the flow of live gas from the main, becausethese installations in general are not easily or safely made in aservice line in the face of a normal flow of gas, or cannot be testedfor leaks.

In known types of interior by-pass installations in which the linertubing is installed working solely from the basement end of the serviceline it is especially difficult to secure a fluid-tight seal at the"blind" end of the service line, and to confirm that an effective sealhas been made at that end. In fact, in all previous types ofinstallations which extend all the way to the main, an effectivetechnique for leakage testing of the blind end liner seal, workingsolely from the building basement, has not been developed. Nor has anyprevious adapter sealing technique permitted effective simultaneoustesting of the seals made at both ends of the line, to the end that bothcan be certified as meeting test standards established for such seals.

In addition, previous interior by-pass liner installations are usuallyrequired to be made using considerable care or skill, with attendanthigh cost due to the prolonged time involved in making and testing theinstallation. Of course, there is a commensurately long interruption ingas service to the building, resulting in other inconveniences.

SUMMARY OF THE INVENTION

Accordingly, it is intended by the present invention to overcome thesedifficulties by providing a method and means by which such interiorby-pass tubing can be conveniently installed within the entire length ofa gas service line extending from a building basement some 25-to 50-feetto the street main, working from only the basement or service head endof the line, yet with assurance that fluid-tight peripheral seals of thetubing against the interior of the existing conduit will be establishedat both ends of the tubing. Thus, no street excavation will be requiredat the location of the gas main, nor anywhere between the main and thebuilding. Since the by-pass will extend beyond the location of anyexisting curb-valve in the line, as a corrollary to the avoidance ofstreet excavation it is also intended by the invention to provide amethod and means to effect such installation without any need forshutting off the flow of gas from the main, i.e., while the service lineis "alive." It will also be noted that any existing curb valve may besubsequently closed to squeeze and flatten the plastic or soft metalliner tubing to shut off the flow of gas in an emergency. Of course, theinstallation procedure must also be safe, and not require unusual orhurried work techniques.

The fluid-tight seal made at each end of the tubing must be easilyinstalled, and must be effective to meet test standards established bygovernment agencies. For example, the Public Service Commission of theState of New York requires that such gas seals in low pressure lines(0.25 p.s.i.g.) be effective to prevent gas leakage at 50 p.s.i.g.exerted continuously for a period of fifteen minutes. The seals of theby-pass installation of the present invention are intended, and in facthave been found to pass such a leakage test.

Perhaps more importantly, the present invention provides a method andmeans to conveniently apply such a gas leakage test to the line, usingcompressed natural gas as a test medium, and to effectively monitor thetest results so that the establishment of an effective seal at each endof the interior by-pass tubing can be certified. Moreover, the gas-tighteffectiveness of the installation can be similarly tested at any futuretime when leakage is suspected.

The installation can be made rapidly, and therefore with considerablesavings in the labor cost as compared with previously known similarinstallations, whether or not they required street excavation. Ofcourse, the time, inconvenience and expense of repairing such otherwiserequired street excavation is entirely eliminated by the presentinvention, and the time of the gas service interruption is in any casesubstantially reduced.

It is also intended to provide a by-pass installation which may be useduniversally throughout a gas service system and in both high and lowpressure lines, requiring only size variation of its component parts toadapt it for use in different diameter lines.

Briefly describing the invention, it employs an adapter attached at eachend of the liner tubing as in known arrangements, but each adapterprovides a pair of spaced-apart expanded gaskets, rather than a singleexpanded gasket, to connect and seal its end of the liner tubing withinthe service line, and a deliberately provided gas-leakage passagebetween the pair of expanded gaskets to permit gas flow from theinterior of the liner (or, more accurately, from the interior of theadapter body as will be described) to the exterior of the liner tubingbetween the referred to pair of expanded gaskets. In addition,respective and temporary gas-tight plugs are installed beyond thedeliberately gas leakage passages at the ends of the liner tubing (i.e.,between each leakage passage and the adjacent liner end) so that, afterthe installation is completed, test pressure, usually compressed naturalgas, can be applied to the interior of the liner from the buildingbasement to test for leaks through the seals at both of its ends. Duringtesting, the test pressure is transmitted interiorly of the liner and,via the gas leak passages, to the exterior of each adapter endconnection, between the pair of expanded gaskets thereat and against theinterior wall of the service line so as to be applied directly to theperiphery of each gasket seal. If any gasket of the two pairs ofexpanded gaskets leaks, a slow drop in test pressure will be observedover a period of time. It will be noted that if but a single gasket wereused at either end, its tightness of seal against the interior of theold service pipeline could not be tested using test pressure appliedonly to the interior of the liner. In contrast, the present inventionpermits test pressure to be applied directly and simultaneously from theinterior of the liner to both of the exterior gasket seals formed inclosely adjacent relation at each end of the line. The innermost gasketof each pair (i.e., that closest to the middle of the pipeline) mustdemonstrate that it is effectively sealed, otherwise loss of testpressure will occur through the existing steel service pipeline which isknown to be leaky, and the outermost gasket of each pair (i.e., thatwhich is adjacent to the end of the tubing) must also demonstrate itstightness to avoid loss of test pressure therethrough in the directionof the end of the tubing. If any of the four gasket seals leaks, thetest pressure will drop.

The deliberate leakage aperture between each pair of sealing gaskets canbe effected by drilling a hole through the steel body of the adapterconnection or, alternatively and preferably, by providing a machine or"running" thread, as distinguished from a tapered pipe threadconnection, between the pair of adapter body portions which form theadapter at each end of the line, the imperfect tightness of such machinethreads permitting sufficient gas leakage to provide an effective testaperture.

Regarding other features of the installation technique, it has beenfound that, to prevent twisting of the plastic liner tubing and toeffectively tighten the adapter connection at each end of the liner byexpanding the pair of gaskets thereat, the service head adapter(adjacent the basement) must be tightened first, after which the blindend adapter (adjacent the gas main) can be more easily and effectivelyinstalled. In addition, the present invention contemplates and providesa method and means whereby the innermost (with reference to the lengthof plastic tubing) of the pair of gaskets on each adapter will beexpanded first and fully secured before the outermost gasket is expandedagainst the interior of the service line, so that tightness of theinnermost gasket is always assured. This ordered sequential expansion ofthe pair of gaskets at each end of the tubing is achieved by restrictingthe turning of the end nut or cap of each adapter. In the presentlypreferred embodiment to be described, a plastic interior abutment collaris disposed within the threaded endcap of each steel adapter to providea relatively hard but temporary shoulder by which turning of the cap onthe steel middle body of the adapter is prevented while force is appliedto the adapter middle body to press against and expand the innermostgasket on the adapter main body. However, continued turning the theadapter endcap causes the screw threads on the shank of the middle bodyto cut and self-tap into the plastic collar, thus permitting the cap tomove against and expand the outermost gasket, on the middle bodycomponent.

The assembly and installation of these end adapters and tubing is madeafter initially installing a temporary, so-called "convenience" valve inplace of the conventional plug in the basement tee at the end of theservice line, as will be described. Further, during certain stages ofthe installation a flexible elastic bag is placed over a projectingnipple on the convenience valve, the tools required for the by-passinstallation being placed within the bag and then manipulated from theexterior of the bag, as will be described. The long rods necessary formoving tools down the interior of the liner tubing during theinstallation procedure extend through an opening which is opposite theneck opening of the elastic bag which holds it on the valve nipple.

The so-called "blind end" adapter adjacent to the gas main is installedhaving a "bullet" type sealing plug within the bore passagewaytherethrough, and beyond the referred to gas leakage passage. After bothof these end adapters are installed within the line so that the by-passis complete, a leakage test is made from the service head end of thetubing using a tool which has a machine threaded and O-ring sealconnection to the service head adapter, as will be described, to permittest gas pressure to be exerted through the aforementioned leakagepassage of the service head adapter commensurately with its exertionthrough the leakage passage of the remotely located blind end adapter.After completion of the test and removal of the testing tool, the"bullet," which has thus far prevented a flow of gas from the main, isremoved from the blind end adapter using a tool passed through thetemporary elastic bag on the convenience valve, after which theconvenience valve is removed and the conventional plug is inserted inthe basement service tee, thus to restore the gas service line to normaloperation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

These and other objects, features and advantages of the presentinvention will become apparent from the following detailed descriptionof the invention, when taken together with the accompanying drawings inwhich:

FIG. 1 is a fragmented and cross-sectional elevation of a gas serviceline in which a by-pass liner tubing is being installed in accordancewith the present invention;

FIGS. 2 and 3 are similar views showing eariler steps during theinstallation;

FIGS. 4, 5 and 6 are enlarged cross-sectional views of only the servicehead end adapter connection, illustrating a sequence of three stages inits installation;

FIGS. 7, 8 and 9 are views similar to FIGS. 4-6, but illustrating threesequential stages during the installation of the blind end adapter;

FIG. 10 is a perspective showing, to a smaller scale, of connectionsmade between short lengths of rod to form a longer rod to be used duringinstallation of the blind end adapter;

FIG. 11 is a cross-sectional and somewhat diagrammatic illustration ofthe method of testing the installation of FIG. 1;

FIG. 12 is an enlarged fragmentary cross-sectional showing of theengagement between the gas pressure test tool and the service endadapter during the test, to further illustrate how testing of theinstallation is performed;

FIG. 13 is an enlarged cross-sectional view of a modified form of endcapwhich may be used on the blind end adapter in accordance with theinvention; and

FIG. 14 is a cross-sectional showing of still another modification ofthe blind end adapter as may be used.

Referring to FIG. 1, in a conventional gas service distribution networka gas main 20 lies buried in the ground under a street generallyindicated by numeral 21. A service line connection tee 22, of steel orother material, is connected as by threads 23 to the top of the gas main20, the connection tee having a threaded cap 24 on its upper end. A gasservice line 25, made of similar steel pipe, extends some 25' to 50'underground from the connection tee 22 into the basement area, generallyindicated by reference numeral 26, of a building whose concretefoundation wall and flooring are respectively indicated by referencenumerals 27 and 28. At its service head end 25a which extends throughthe building wall 27, the gas service line 25 is connected by a basementservice tee 29 to a riser pipe 30 which, through a gas service shut-offvalve 31, leads to a gas meter (not shown) as is well known. AlthoughFIG. 1 illustrates a convenience valve 32 coupled to the basement tee 29by a nipple 33 for purposes as will be described, those skilled in theart will understand that the basement tee 29 is normally closed by astandard pipe plug (not shown) which is threaded into the end opening ofthe tee in place of the convenience valve nipple 33.

At a location within the length of the gas service line 25 between itsstreet or "blind" end 25b and its service end 25a a curb valve 34 isusually installed, such being a conventional gate valve for shutting offthe flow of gas in the line. The curb valve has a handle 34a which isreached by removing the valve box cover 35a, located at ground level, ofa curb valve box, generally indicated by reference numeral 35, withinwhich the valve 34 is exposed. As is well known, the curb valve isnormally left open, and sometimes deteriorates after many years.Moreover, if one were to look through an opened curb valve 33 from theservice end 25a of the line, a pair of radially inward projecting lugs(not shown) which secure the valve seat in the valve body, as well asshort, radially inward projecting portions of the valve spindle andvalve gate (not shown) would be visible, and would tend to constrict theopening and interfere with the intended installation of the by-passtubing arrangement. Accordingly, where a curb valve 34 is located withinthe service line, reaming out of these interiorly projecting portions ofthe curb valve will normally be necessary. Reaming or scraping may alsobe necessary to clean off interior rust or other scale, or to removeinterior flanges or any other projecting portions of the service lineprior to installation of the by-pass liner.

The present invention provides an interior by-pass liner assemblygenerally indicated by reference numeral 40, for bypassing any leaks,such as a leak 25c, along the length of the gas service line 25, asmight have occurred by breakage, corrosion or other deterioration.Although the by-pass liner tubing 41 is preferably high density, highmolecular weight, flexible polyethylene plastic tubing, it will beunderstood that other suitable plastic or metal tubing might beemployed. Typically, 1" C.T.S. (Copper Tube Size) stiff polyethylene gastubing having 0.090" wall thickness and an outside diameter of 11/8"would be used as a liner within a 11/4" steel pipe service line, theinside diameter of which is actually 13/8". In addition to the tubing 41which in the preferred embodiment extends the entire length of theservice line 25 from a "blind" end location adjacent the gas main 20 toclosely adjacent the basement or service end 25a of the line 25, theby-pass liner assembly includes a blind end adapter, generally indicatedby reference numeral 42, and a service head end adapter, generallyindicated by reference numeral 43, which are respectively attached tothe ends of the tubing 41, as indicated.

The liner assembly 40 is shown in FIG. 1 as fully assembled andinstalled within the service line 25. Although its adapter componentsand tubing might be pre-attached and actually installed in suchassembled form, the assembly 40 is preferably assembled as theinstallation proceeds, in manner as will be described. Thus, theassembly 40 is intended to be furnished at the job site disassembled inwhat may be termed a kit of assemblable parts or components, these beinga reel (not shown) of the plastic tubing from which the liner tubelength will be cut to the exact size required, and other componentswhich will be assembled during the installation, such as the service endadapter 43, the blind end adapter 42, and others as will be seen.

Further referring to FIG. 1, each of the adapters 42 and 43 as installedhas a longitudinally spaced apart pair of radially expanded gaskets,respectively indicated by reference numerals 44, 45 and 46, 47, eachforming an external peripheral seal between the adapter and the interiorof the service line 25, and means forming a gas leakage passage betweeneach of these pairs of gaskets, as generally indicated by the respectiveconnection interfaces 48 and 49 therebetween, these leakage passagesbeing provided by unsealed threaded connections and abutments betweencertain adapter component parts as will be described. Thus, and as willbe seen, the by-pass assembly 40, and therefore in effect the tubing 41has a gas leakage passage at each of its ends, extending from theinterior of the by-pass liner to its exterior, at respective locationsbetween the gasket pairs at each end, which have been expanded intoperipheral sealing engagement with the interior of the service line 25.As previously noted, these gas leakage passages provide the means fortesting the installed liner assembly 40 to confirm that the line willnot leak when the flow of service gas is resumed.

Before proceeding with a description of the manner of installing andtesting the by-pass assembly 40, reference is made to FIGS. 4 and 7which respectively illustrate the component elements of the blind endadapter 42 and of the service end adapter 43 in assembled but not yetfully installed condition.

Referring first to FIG. 4 which illustrates the service end adapter 43,in addition to what will be referred to as the outer expansible gasket46 and the inner expansible gasket 47 (with reference to the middle ofthe tubing 41), the service end adapter 43 has a tubular steel inner ormain body generally indicated by numeral 50, to the serrated shank end51 of which the plastic tubing 41 will be attached by a crimped-on metalsleeve 52. A pair of nitrile rubber O-rings 53, 54, mounted inappropriate peripheral grooves of the shank (not numbered), provide afluid-tight seal between the tubing 41 and the adapter main body shank51. The end of the tubing abuts against a peripheral abutment shoulder55 of the adapter main body 50. The sleeve 52 which, of course, waspreviously mounted on the tubing 41, is slid over the attachment, andover the peripheral shoulder 56 into abutment against a second abutmentshoulder 57. The sleeve 52 is crimped on to the tubing 41 and shank 51by three peripheral extending crimps 58a, 58b, 58c which are formed by acrimping tool (not shown). A longitudinal slot (not shown) in the sleevethrough which the tubing and shoulder 55 may be seen provides assurancethat the tubing 41 is butted against shoulder 55 before crimping.

The adapter main body 50 further has a conical shoulder 60 which tapersinwardly, at an angle of about 35°, from the outer diameter 61 of themain body to the smaller diameter threaded extension 62 at the front endof the body, as shown. The central bore 50a of the service end adaptermain body has internal left-hand coarse machine threads 63 along thatportion of its length which passes through the extension 62, for useduring installation and for testing purposes as will be described. Theexternal threads 62a on the extension 62 are right-hand coarse machinethreads which provide a running fit and therefore do not provide afluid-tight seal.

The service end adapter 43 further has a steel inner or middle body 65whose outer diameter 66 is the same as the outer diameter 61 of the mainbody 50. It has a widened internal bore 67 having internal threads 67awhich mate with the threads 62a of the main body extension 62, on whichthe middle body is mounted. The smooth central bore 68 of the tubularmiddle body 65 has a diameter only slightly larger than the diameter ofthe main body bore 50a to slidably receive an assembly holding tool 85,and a leakage testing tool (FIG. 12) as will be described. In mannercorresponding with the same features of the main body 50, the middlebody 65 has a conical shoulder 69, and a front extension 70 havingexternal right-hand coarse machine threads 70a.

The outer and inner gaskets 46 and 47 are made of Buna-N rubber orsimilar resilient plastic or other radially expandable elastic material,and are initially mounted respectively on the middle body extension 70and on the main body extension 62, as shown. The inner diameters ofthese gaskets approximate the outer diameters of these extensions sothat the gaskets are slidable thereon, and the outer diameters of thegaskets are slightly less than the internal diameter of the service line25 against which they will be urged and will seal. It will be noted thatboth gaskets 46 and 47 are chamfered internally, as at 46a and 47a, toconform with the shapes of the respective conical shoulders 69 and 60against which they initially rest and on which they will be expanded.Respective metal compression rings 72 and 73 are slidably mountedadjacent the gaskets 46, 47, gasket 47 and ring 73 being abutted andretained on the main body extension 62 by the rearwardly facing abutmentshoulder 74 of the middle body 65 when the latter is threadedly mountedon the extension 62, as shown.

The outer gasket 46 and its compression ring 72 are abutted and retainedby a cylindrical endcap 75 which has internal threads 76 by which it ismounted on the corresponding threads 70a of the middle body extension70. The endcap 75 has a rearwardly facing abutment shoulder 77 whichengages the metal compression ring 72. The endcap further has aring-shaped insert liner collar 78, made of stiff plastic such as nylon,which is firmly secured by any conventional means within the internalperipheral surface 79 of the cap for a purpose to be described. However,it should be noted that the internal diameter 78a of the plastic linercollar 78 is substantially equal to the root diameter of the middle bodyexternal threads 70a, and that the outer diameter 78b of the collar 78,which corresponds with the cap internal surface 79, is slightly greaterthan the outside diameter of the threads 70a. Further, the cap 75 has acastle-like configuration along its front-end face 80, formed by a pairof diametrically opposite spanner notches 81 which will be engaged bysimilar diametrically opposed spanner projections 91 on a tubularspanner tool 90 for tightening the cap 75 during the adapterinstallation procedure. The external diameter 90a of the tool 90 issmaller than the internal diameter of the service line 25, and theinternal axial bore 92 of the tool is at least as large in diameter asthe bore of the adapter middle body 68 so that the spanner 90 will beslidable over the rod-like holding tool 85.

Similarly, and referring now to FIG. 7 which shows the blind end adapterpositioned, but not yet installed within the service line 25, the blindend adapter 42 has, in addition to its expansible outer gasket 44 andinner gasket 45, a tubular steel inner or main body generally indicatedby reference numeral 95, which has a serrated shank end 96 on which theplastic tubing 41 will be attached by a crimped-on metal sleeve 97. Theintended fluid-tight seal between the tubing 41 and the shank 96 isassured by a pair of nitrile rubber O-rings 98, 99 which are mounted inappropriate peripheral grooves of the shank (not numbered). The end ofthe tubing 41 seats against an abutment shoulder 100 of the adapter mainbody 95, and the metal sleeve 97 is mounted on the peripheral shoulder101 of the adapter body, its end seating against a second abutmentshoulder 102. The sleeve is crimped on to the tubing 41 and shank 96 bythree peripheral extending crimps 103a, 103b and 103c.

The blind end adapter main body 95 further has a concical shoulder 105which tapers inwardly from the outer diameter 106 of the main body tothe smaller diameter extension 107 at the front end of the body, asshown. Forward of the shoulder 105 the extension 107 has externallefthand coarse machine threads 107a which provide a running fit andtherefore do not provide a fluid-tight seal, and it will be noted thatthe axial bore 108 of the main body extends smoothly through its entirelength.

The blind end adapter 42 further has a steel outer or middle body 110which is similar to the middle body 65 of the service end adapter. Ithas a smooth central bore 111, and an outer diameter 112 which is equalto the outer diameter 106 of the adapter main body 95. The middle bodyfurther has a widened internal bore 113 having internal threads 113awhich mate with the threads 107a of the main body extension 107, onwhich the middle body 110 is mounted. Similar to the same features ofthe main body 95, the middle body 110 has a conical shoulder 114 and afront extension 115, the latter having external left-hand coarse machinethreads 115a.

The soft Buna-N rubber outer and inner gaskets 44 and 45 are slidablymounted respectively on the middle body extension 115 and on the mainbody extension 107, each being followed by a metal compression ring 116and 117, respectively. The gasket 45 and ring 117 are abutted andretained on the main body extension 107 by a rearwardly facing abutmentshoulder 118 of the middle body 110 when the latter is threadedlymounted on the extension 107 as shown. Except as previously noted, theshapes, sizing and arrangement are the same as those described inconnection with the service end adapter 43.

However, the outer gasket 44 and its compression ring 116 are abuttedand retained by the rearwardly facing abutment shoulder 120 of aslightly different, elongated endcap 121 which is threadedly mounted onthe middle body extension threads 115a by corresponding left-handinternal cap threads 121a. The endcap 121 has a ring-shaped insert linercollar 123 as does the service end adapter cap 75, the liner beingsecured by any conventional means within the internal peripheral surface124. The liner collar 123 is made of stiff plastic, such as nylon, for apurpose to be described. However, it should be here noted that theinternal diameter 123a of the plastic collar 123 is substantially equalto the root diameter of the middle body external threads 115a, and thatthe outer diameter 123b of the collar 123, which corresponds with thecap internal surface 124, is slightly greater than the outside diameterof the threads 115a. Further, the blind end adapter endcap 121 has arod-like tool engagement pin 125 attached to extend diametrically acrossthe otherwise open tubular bore of the cap, for use during theinstallation procedure.

Also illustrated in FIG. 7 in position within the blind end adapter 42is a short-length, solid rod-like installation tool 130, which forconvenience will be referred to herein as a "bullet". The bullet 130mounts a pair of spaced apart O-rings 131 and 132 whose diameters aresuch as will form a fluid-tight seal within the adapter middle body bore111 when the bullet is inserted therein.

At its forward end the bullet 130 has a diametrally extending recess orchannel 133 which receives and engages the diametral pin 125 of theadapter endcap so that, by means of the bullet, the cap 121 can betwisted and tightened on to the adapter middle body 110 during theinstallation procedure, as will be described. For the same purpose, theopposite end of the bullet 130 mounts a "quick-connect" type fitting134, which is preferably of the type sold by Dzus Fastener Co., Inc, ofWest Islip, N.Y., under the trademark "Anchor-Cam," and to which a chainof similarly connected extension rods is connected during theinstallation procedure both to tighten the adapter cap and, later, todisengage and retrieve the bullet 130 so as to restore the flow ofservice gas in the installed service line by-pass, as will be described.

An alternative, flow fuse type endcap 140 which may be substituted forthe endcap 121 of the blind end adapter is shown in FIG. 13. Thisembodiment includes internal threads 141 by which the cap is mounted onthe extension threads 115a of the adapter middle body 110, a plasticinsert liner collar 142, and a diametrally extending tool engagement pin143, as in the cap 121. However, the forward end of its elongated andtapered steel body mounts a stiff plastic insert 144 whose central bore145 is conically flared towards its forward end, as shown. A flow fuse146 has a stem 147 which is very loosely mounted within the bore 145 toguide the slidable movement of the plug, yet not significantly obstructthe normal flow of service gas therethrough when the service line 25 isrestored to operation. The head 148 of the flow fuse is axially splinedaround its outer periphery, as indicated at 148a to similarly permit thenormal flow of gas around the fuse head, yet provide for axial slidablemovement of the fuse head within the cylindrical cap bore 149 when thefuse opens and closes in response to gas pressures.

The flow fuse 146 is a normally open fuse as shown, and includes a coilspring 150 which urges its head 148 away from the forward end of the capand into engagement at its tip 148b against the diametral pin 143 toretain it in such open position. Thus, during and after the installationof the blind end adapter having such cap 140 within the service line 25,the flow of gas within the service line and therefore, within the tubing41, will flow through the flow fuse. However, this flow fuse will closein response to the intended leakage test pressure, of about 50 p.s.i.g.,when applied within the by-pass liner tubing 41 from the service headend of the line, as will be described. When closed by such testpressure, a soft head gasket 151 seals against the end 145a of theplastic insert bore 145, to stop the flow of gas service through thebore 145. When the pressure test is completed and the test pressurewithin the by-pass is discontinued, the flow fuse will open in responseto the bias of the coil spring 150, and the flow of normal service gaswill resume within the by-pass line.

FIG. 14 illustrates another modified form of blind end adapter 42a forstopping the flow of line service gas in a different manner when theintended line leakage test is to be performed. This adapter 42a issimilar to the previously described blind end adapter 42 (FIG. 7)including its end cap 121, but has a modified form of middle body 155.

That is, its inner or main body 95 is attached to the liner tubing 41 bya crimped on sleeve 97 as previously described, and the adapter includesa pair of expansible elastic gaskets 44, 45 and respective steelretainer or compression rings 116, 117. Moreover, the modified form ofmiddle body 155 has external threads 115a on its forward extension,which engage the internal threads 121a of the endcap 121. The endcapalso includes a diametral pin 125. However, the middle body 155 has athreaded internal bore 156 whose right-hand threads are preferablymachine type, running threads for easy removal of a threaded plug 157whose external threads 158 are engaged therewith when the plug 157 isinserted, as shown. The plug includes a conical shoulder 159 at itsrearward end, which might be gasketed, but in any event seats and sealsagainst the periphery of an interior conical shoulder 160 within thebody 155. The plug 157 is installed and removed using a rod-like tool161 having a projecting left-hand threaded tip 162 which is engageablewith a correspondingly threaded recess 163 of the plug.

As in the case where a flow fuse type cap 140 is used, the modified formof blind end adapter 42a must be installed while live service gas isflowing through the service line 25, during which installation theendcap pin 125 must be accessible. However, when the line leakage testis to be performed (as will be described), the plug 157 is inserted tostop the flow of service gas during the test. Upon completion of thetest, the plug 157 is removed to permit the flow of service gas toresume.

From the foregoing descriptions of the preferred embodiments (as shownin FIGS. 4 and 7) of both the service end adapter 43 and the blind endadapter 42 it will be apparent that, because the threaded connectionsbetween their respective main and middle body components arerunning-thread connections which do not provide fluid-tightmetal-to-metal contact seals, their respective gas leakage passages 48and 49 (FIGS. 1, 4 and 7) will be formed by the unsealedsurface-to-surface connections provided by the threads 107a, 110a and62a, 67a and between the respective steel rings 117 and 73 and theiradjacent middle body abutment shoulders 118 and 74, respectively. Thus,these gas leakages extend through these adapters from their interiortubular bores to the exteriors thereof, at respective locations betweenthe gasket pairs 44, 45 and 46, 47 as previously mentioned.Alternatively, the gas leakage passage from the interior of the adapterto its exterior might be formed by drilling an aperture through theadapter middle body element of either the service end adapter (notillustrated) or the blind end adapter, such as the aperture 165 of themodified blind end adapter middle body 155 (FIG. 14), at a location suchthat the aperture will not be obstructed by the threaded forward endextension of the connecting main body element after the installation iscomplete. In such alternate embodiment, the threaded connection betweenthe main and middle body elements might be a tapered pipe thread orotherwise sealed to provide a very tight fit between these elements, yetthe required gas passage for testing purposes, as will be described, isstill provided. It should also be noted that for purposes of the test,the location of the leakage aperture 165 must be on the service lineside of the line plug, such as the bullet 130 (FIG. 7), or the flow fuseat 146 (FIG. 13), or the plug 157 (FIG. 14), which stops the flow ofservice gas during the test.

Turning now to the procedure by which the liner by-pass installation ismade, as an initial step any curb valve in the gas service line 25, suchas the curb valve 34 (FIG. 1), is temporarily closed while theconvenience valve 32 is installed in place of the conventional plug (notshown) at the end of the basement service tee. If the line 25 does notinclude a curb valve, or if through deterioration the curb valve cannotbe closed, the convenience valve 32 can be installed "on the fly," i.e.,by removing the plug and quickly threading the convenience valve nipple33 in its place. Of course, the convenience valve 32 is closed wheninstalled, and has an open pipe nipple 36 projecting from its interiorfacing end, through which the entire installation procedure isconducted. The curb valve 34 may then be opened.

Using any conventional techniques the interior of the service line 25including the curb valve 34 is then reamed to remove projections orrough edges which might later cut through the plastic by-pass tubing 41.

Thereafter, the convenience valve 32 is closed, and the blind endadapter 42 (FIG. 7) is assembled. Its soft Buna-N inner gasket 45 isfirst mounted on the tubular main body 95, against the peripheralexpansion shoulder 105 of the latter. The gasket 45 is followed by themetal pressure ring 117. Next, the tubular middle body 110 is threadedon to the main body 95 of the adapter, to a position beyond whichfurther tightening of the threaded connection would cause pressure onthe ring 117 to force the gasket 45 to ride up on, and expand againstthe tapered shoulder 105. The second expansible gasket 44, followed bythe metal pressure ring 116 and the end cap 121, are then similarlymounted on the threaded extension 115 of the adapter middle body 110.That is, the cap 121 is tightened, to a position where furthertightening would press the pressure ring 116 against the second gasket44 and cause it to ride up on, and expand against the tapered shoulder114 of the middle body. When the cap is tightened to this position itsplastic insert collar 123 is immediately adjacent to the end of thethreaded middle body extension 115, as seen in FIG. 7. The plasticinsert 123 thus provides a semi-hard shoulder against the end of themiddle body extension to prevent further engagement movement of the capthereon under normal twisting pressure until such further movement isdesired, as will be described.

The interior sealing bullet 130 is then inserted into the assembledblind end adapter so that its recess channel 133 engages the diametralpin 125 of the endcap, and its pair of then greased O-rings 131, 132effect a gas-tight seal against the smooth interior bore 111 of theadapter middle body.

The thus assembled blind end adapter 42, with the bullet 130 therein, isthen attached to the end of the plastic tubing 41 which will serve asthe by-pass liner, the attachment being by crimping on of the externalmetal sleeve 97 to provide a fluid-tight connection between the tubing41 and the main body shank 96 as previously described. At this time theplastic tubing is of indefinite length, being wound upon the supply reel(not shown) on which the tubing is furnished from the manufacturer.

Referring again to FIG. 1, a neoprene rubber inflation bag 170 is thenfitted on to the open projecting end of the convenience valve nipple 36.In a typical installation the bag 170 (FIG. 1) may have a 1"-diameterelastic collar 170a which stretches to fit over the 11/4" outsidediameter of the nipple 36 to thus form a temporary gas-tight seal. Forsuch a typical installation the bag 170 may be about 18" long and haverelatively square 8"×8" shape along its length. At its opposite orrearward end the bag 170 has a 3/4"-diameter opening 171 through whichthe blind end adapter 42, attached to the tubing 41 as previouslydescribed, is then inserted into the bag.

Referring now to FIG. 2, the convenience valve 32 is then opened usingits handle 32a. After the curb valve 34 has been opened the bag 170 willbe inflated by the natural flow of service gas through the service line25 from the main 20, the bag 170 being sealed at its opposite end by thegas-tight fitting relation of the elastic aperture 171 around the linertubing 41 which is at the time projecting therethrough, as shown. Thecurb valve 34 may remain closed until the blind end adapter 42 has beeninserted into the service line and moved to the location of the curbvalve, as will now be described. Manipulating the tubing 41 from theexterior of the bag 170, the tubing is pushed in the direction of thearrow A, and fed through the bag 170 to move its attached blind endadapter 42 into and down the service line 25. When the curb valve isopened, the blind end adapter is pushed through and past the curb valve34, to abutment against the far wall of the main connection tee 22.Where it is exposed outside of the bag aperture 171, the tubing is thenmarked with a reference point (not shown), whereupon it is backed out ofthe bag 170 a predetermined distance (equal to the length of theattached bag 170, plug the length of the convenience valve 32 includingits nipple 33 and any appropriate portion of its nipple 36, plus thelength of the basement tee 29, plus a distance equal to, or slightlygreater than that length of the assembled service end adapter 43 (FIG.4) which extends from the end of the cap 75 to the tube abutmentshoulder 55 on the adapter main body 50, and plus a distance equal to orslightly greater than the diameter of the main connection tee 22), atwhich point the tubing 41 is cut, thereby severing exactly the neededlength thereof from the reel supply.

Next, the service head adapter 43 is attached and assembled on theexposed end of the tubing 41 in the manner previously described. Thatis, and referring briefly to FIG. 4, the end of the tubing 41 is crimpedon to the adapter main body 50, whereupon the gasket 47 and compressionring 73 are slidably mounted on the main body extension 62. The middlebody 65 is then threaded on to the extension 62 to the point where thegasket 47 abuts the expansion shoulder 60 of the main body 50. Thegasket 46, compression ring 72 and endcap 75 are then similarly mountedon the threaded middle body extension 70, the cap being threaded on astightly as it will move by manual twisting, at which point its insertcollar 78 will be in abutment with the end of the body extension 70, andthe gasket 46 will be against the middle body expansion shoulder 69, asseen in FIG. 4.

Continuing to refer to FIG. 4, but while the service head adapter 43 isstill exposed in the basement though attached to the tubing 41, therod-like service end adapter holding tool 85 is attached to the servicehead adapter 43 by threading its external left-hand end threads 86 intothe internal left-hand threads 63 of the main body. An O-ring 87 at theinner end terminus of the threads 86 of the tool provides a cushioned"land" against the end of the adapter body extension 62, indicating whenthe tool is fully inserted into the adapter 43.

Referring now to FIG. 3, using the holding tool 85 to again move thetubing 41 down the service line 25, the service head end adapter 43 ispushed through the bag aperture 171 into the bag 170 and thence throughthe convenience valve 32 and basement tee 29 to its intended location asillustrated, within the service line 25. Because the installation isbeing made "in the blind", so to speak, this positioning of the servicehead adapter 43, and thus the correct positioning of the blind endadapter 42 as seen in FIG. 3, is predetermined with reference to thelength of the holding tool 85 which must be inserted into the bag 170.That is, the distance inward beyond the bag aperture 171 which thetubing 41 must be moved is equal to that which the tubing 41 was "backedout" of the bag from the position of the tubing as shown in FIG. 2 forcutting the tubing to the correct length, as previously described, minusa distance equal to the diameter of the main connection tee 22 (toposition the blind end adapter 42 as shown in FIG. 3 rather than asshown in FIG. 2). For the purpose, an appropriate reference point (notshown), measured from the service head adapter shoulder 55 (FIG. 4), ismarked on the shaft of the holding tool 85 before the adapter 43 isinserted into the bag aperture 171.

It will be noted that the bag 170 continues to be inflated while theassembly 40 is being thus positioned within the service line 25 because,although the bullet 130 within the blind end adapter 42 prevents gasflow within the tubing 41, gas from the main 20 is free to flow withinthe service line 25 exterior of the tubing 41. It will further be notedthat the size of the bag aperture 171 must be small enough to tightlyengage and seal against the shaft of the holding tool 85 as the latteris passed therethrough.

The service head and adapter 43 will now be tightened and thus attachedwithin the service line 25 in its position shown in FIG. 3, and for thispurpose the tubular spanner wrench 90 is mounted and moved in thedirection of arrow B on the shaft of the holding tool 85, as illustratedin FIGS. 3 and 4, until its spanner projections 91 engage the spannernotches 81 on the adapter endcap 75 as seen in FIG. 5. Of course, thespanner tool is forced through the bag aperture 171 into the bag 170 andthence into such engagement, as will be understood. As indicated in FIG.3, the wrench 90 has handles 93 at its opposite end which remain outsideof the bag 170, by which the wrench may be turned.

Referring to FIG. 5, and recalling that the holding tool 85 hasleft-hand threads 86 whereas the endcap 75 has internal right-handthreads 76, the service end adapter cap 75 may now be turned clockwiseusing the wrench 90 while the holding tool 85 retains the adapter mainbody 50, and consequently the tubing 41, in position and againstturning. Because of the abutment of the cap insert collar 78 against theend of the adapter middle body 65, such clockwise turning of the capwill cause concurrent clockwise turning of the middle body 65 and,because of the somewhat hard nature of the plastic of which the collar78 is made, the cap will not itself further advance on the middle body65. Thus, the middle body 65 is threadedly tightened on to theright-hand threads 62a of the adapter main body extension 62 and, asillustrated in FIG. 5, the gasket 47 is forced on to the expansionshoulder 60 and is expanded into sealing engagement with the interiorwall of the service line 25, the force being transmitted by theadvancing middle body 65 against the compression ring 73 and thenceagainst the gasket 47.

As the gasket 47 becomes fully expanded as seen in FIG. 5 and continuedtightening force is exerted on the spanner tool 90, the resistance tofurther axial movement of the adapter middle body 65 on the main bodythreads 62a becomes greater than the resistance of the plastic materialof which the insert collar 78 of the cap 75 is made (which resistancehas thus far prevented the cap from further threaded movement on themiddle body extension 65), whereupon the cap 75 begins to turn on theextension threads 70a as the latter begin to cut and self-tap into theplastic material 78. Thus, continued right-hand twisting of the spannertool 90 while holding the holding tool stationary as illustrated in FIG.5 will cause the gasket 46 and compression ring 72 to move axially alongthe middle body extension 70 as the cap 75 threads inwardly, and thegasket 46 rides up on to, and is radially expanded by the middle bodyexpansion shoulder 69 into peripheral sealing engagement with theinterior wall of the service line conduit 25, as illustrated in FIG. 6.

Continuing to refer to FIG. 6, the service head end adapter 43 has nowbeen tightly secured within the service line 25, whereupon the spannertool 90 and holding tool 85 are removed in the direction of arrow C.Because the adapter is tight, it will be noted that the holding tool 85can be easily loosened from its left-hand threaded connection within theadapter main body 50.

It will also be noted that, as the gaskets 46 and 47 become tightlysealed against the interior wall of the service line 25, the flow ofservice gas from the gas main 20, which cannot enter the liner 41because the bullet plug 130 (FIG. 7) is within the blind end adapter 42,is now completely stopped, and the inflation bag 170 (FIGS. 2 and 3)will deflate and collapse as the spanner and holding tools are withdrawnthrough the bag aperture 171. In fact, such collapse of the bagindicates an effective seal has been made, and the bag 170 can thereforebe removed from the valve nipple 36 without fear of leakage of gas. Ifthe bag fails to collapse completely, an effective gas-tight seals hasnot been formed at one of either the service end adapter or at thebullet 130, and appropriate corrective action would be required.

The sequence in which first the seal 47 and then the seal 46 is made, isan important feature of the invention by which full and effectivesealing of the innermost gasket 47, which is the more important gasketof the pair 46, 47, can be assured. Moreover, the full securing of thenearer service end adapter 43 within the service line 25, prior toattempting to tighten the remotely located blind end adapter 42, hasbeen found to result in a more effective installation, which is achievedwith less difficulty than were the blind end adapter attempted to besecured in place first.

The blind end adapter 42 will now be tightened and sealed in itsposition with the line 25 as shown in FIG. 3, using a blind end adaptertightening tool as generally indicated by reference numeral 180 in FIG.10. Because the tool must extend from the basement or service end 25awithin and down the entire 25' to 50' length of the by-pass liner tubing41 to reach the blind end adapter adjacent to the gas main 20, thetightening tool 180 is preferably formed by connecting in tandem aseries of shorter length tool shank sections 181, each about 2' or 3'long, as the tool is being inserted into the line from the buildingbasement area 26. Although these sections might be connected in anyconvenient manner such as by threaded couplings (not shown), they may beconveniently connected and disconnected by employing quick-connectcoupling elements on their respective ends, such as the aforementioned"Anchor-Cam" female connector elements 182 on one end, and co-matingmale connector elements 183 on the other end of each shank section 181,as shown in FIG. 10. At least the fitting 182a on the leading end of thefirst shank section must be engageable with the quick-connect fitting134 (FIG. 7) on the inner end of the bullet 130 which is in the blindend adapter 42.

It will also be understood that all of these rods and rod couplings musthave smaller diameters than any of the adapter body bores 68 and 50a ofthe service end adapter 43 (FIG. 4) or the blind end adapter bore 108(FIG. 7).

Starting with the tool shank section 181 having the fitting 182a thereon(FIG. 10), the blind end adapter tightening tool 180 is introducedthrough the convenience valve 32 into and down the length of the tubing41. It will be noted that, because there is no flow of service line gas,no inflation bag, such as the bag 170 (FIG. 1) need be used at thistime.

Referring now to FIG. 8, the tool 180 reaches and connects on to thebullet 130 within the blind end adapter, the spring-loaded femalequick-connect fitting 182a snapping into engagement within the malefitting 134 on the end of the bullet, as shown.

Because the bullet groove or channel 133 at its forward end is alreadyin engagement with the blind end adapter cap pin 125, clockwise turningof the tool 180 will cause tightening of the left-hand threaded endcap121 and, concurrently, of the adapter middle body 110 on to theleft-hand threaded main body extension 107. The middle body 110 movesconcurrently with the cap 121 because of the shoulder abutment formed bythe plastic insert collar 123 of the cap against the end of the middlebody extension 115, whose resistance to turning force is greater thanthat of the threaded connection between the middle body 110 and the mainbody 95. Thus, as it threads inwardly along the main body extensionthreads 107a, the middle body 110 pushes the compression ring 117 andthe gasket 45 therealong, causing the gasket 45 to ride up on, andradially expand against the main body expansion shoulder 105 until thegasket is fully expanded into peripherally sealing engagement with theinterior wall of the service line conduit 25, as seen in FIG. 8.

The increased resistance to further twisting movement encountered by themiddle body 110 as the gasket seal 45 becomes fully formed, overcomesthe resistance to turning as has thus far been afforded by the nature ofthe plastic material of which the cap insert collar 123 is formed.Accordingly, continued twisting of the tightening tool 180 in theclockwise direction causes the endcap 121 to move and tighten on themiddle body extension threads 115a, the steel threads 115a cutting into,and self-tapping the plastic collar 123. Such tightening is continued asthe gasket 44 is now moved against and expanded on the expansionshoulder 114 of the adapter middle body 110, the cap 121 exertinglongitudinal force on the longitudinally slidable gasket compressionring 116 which, in turn, transmits such force to the gasket 44. When thegasket 44 has been fully expanded into gas-tight sealing relationagainst the periphery of the interior wall of the service line 25 asseen in FIG. 9, the blind end adapter is fully installed, and thetightening tool 180 is removed.

As was the case with the service end adapter 43, it will be noted thatthe innermost gasket 45 of the blind end adapter 42 is tightened first,which provides greater assurance that an effective seal at this, themost important gasket of the gasket pair 44, 45, has been achieved.

The tool 180 is removed by twisting it only one-quarter turn in thecounterclockwise direction to quick-release the cam connection betweenthe female tool connection element 182a and the bullet connector element134. In this regard, it should be noted that this spring-loadedengagement connection must not be as tight or as stiff as the similarconnections 182, 183 (FIG. 10) between the tool shank sections 181,otherwise the tool sections would, upon such counterclockwise turning ofthe tool 180, disengage and cause disassembly of the tool section withinthe tubing 41, yet the endmost tool shank section would not bedisengaged from the bullet.

The by-pass liner installation 40 is now complete, but must be testedfor possible gas leakage, as will now be described with reference toFIGS. 11 and 12. In the presently preferred embodiment, compressednatural gas pressure at 50 p.s.i.g. will be applied into the by-passsystem 40 continuously for a period of 15 minutes from a source 200through a tubular testing tool 201 which will be connected to theservice head end adapter 43, as will now be described.

The inflation bag 170 is now again connected by its elastic collar 170ato the convenience valve nipple 36, the convenience valve 32 still beingin opened condition. The tubular tool 201 is connected at its rearwardend to the test gas source 200 through a valving and pressure meterarrangement, generally indicated by numeral 202 in FIG. 11. Itsconnection to the meter and valve is preferably via a pivotable thoughair-tight quick-connect coupling generally indicated by numeral 206. Theforward end of the tool 201 is then inserted through the bag aperture171 and bag 170, and through the convenience valve 32 and basementservice tee 29, into the service line 25 and, ultimately, into theservice end adapter middle body bore 68.

As seen in FIG. 12, the forward end of the tubular testing tool 201 isexternally threaded as at 203 to be received in the left-hand threads 63within the bore 50a of the service end adapter main body extension 62,and it will be noted that these are coarse machine threads, whichprovide a running fit and are not gas-tight. Thus, test gas pressurewill seep through these threads 63, 203 when applied from the tool 201into the mainbody bore 50a.

The tool 201 further has a pair of external, longitudinally spaced apartresilient O-rings 204, 205 which provide a peripheral gas-tight sealbehind these threads 62a, 203, within the smooth bore 68 of the adaptermiddle body 65.

It should also be noted that the spacing, or even a metal-to-metalabutment, between the end of the adapter main body extension 62 and theinternal end shoulder within the widened bore 67 of the adapter middlebody 65 permits gas to pass therebetween, and that, as previously noted,the connection between the middle body threads 67a and the adapter mainbody threads 62a is not gas-tight. Gas will also seep through themetal-to-metal abutment interface between the middle body abutmentshoulder 74 and the compression ring 73. Thus, the passage 49 of theadapter 43 is formed by these gas leakage passages, yet the test gaswill not leak past the O-rings 204, 205 which are mounted on the tool201 for sealing the middle body bore 68 on the service end side of thepassage 49.

Similarly, and referring briefly to FIGS. 7 and 9, the gas leakagepassage 48 of the finally installed blind end 42 is formed by thespacing between the end of the adapter main body extension 107 and theinternal abutment shoulder within the enlarged bore 113 of the adaptermiddle body 110, and by the running fit between the main body extensionthreads 107a and the internal threads 113a of the middle body, and bythe leakage permitted by the metal-to-metal abutment between the endshoulder 118 of the middle body 110 and the compression ring 117. TheO-ring seals 131, 132 on the bullet 130 (FIG. 7) provide a plug whichwill prevent test pressure leakage through the end of the blind endadapter 42, at a location beyond (i.e., on the gas main side of) the gasleakage passage 48.

Referring again to FIGS. 11 and 12, after the tool 201 has beenthreadedly connected to the service end adapter 43, 50 p.s.i.g. of testpressure is applied therethrough by opening and then closing the valve202a, the pressure being shown on the gage 202b. Because there shouldnot be any pressure therein at the time, the inflation bag 170 shouldremain collapsed during the test. However, although it therefore neednot be used during the test, use of the bag 170 at this time serves as aprecaution against any blow-back of gas during the test, if certainseals are ineffective, as will be understood.

During the test, 50 pounds per square inch of test gas pressure ismonitored for 15 minutes via the adapter leakage passages 48 and 49 tothe peripheral spaces between each of the longitudinally spaced apartgasket pairs 44, 45 and 46, 47 of the respective adapters, and alsowithin the interior of the by-pass tubing 41. If the by-passinstallation 40 is in any way unsound, some drop in pressure will bedetected on the gage 202b, which senses the pressure remaining withinthe tubing 41.

It will be noted that the exact location of the test gas leakage whichcauses the drop in pressure will not be known. That is, the testpressure drop could be due to leakage through any one of the four gasketseals 44, 45, 46 or 47; or through the bullet O-rings 131, 132; orthrough the test tool O-rings 204,205; or through either of the crimpedconnections between the ends of the liner tubing 41 and the respectiveadapter main bodies 50 and 95; or through a tear or other defect in thetubing 41 itself. If such loss of test pressure does occur, the entireinstallation 40 must be rechecked to determine the leak source.

After a successful pressure test has been performed, the test tool 201is removed and, if not already in place, the inflation bag 170 must beconnected to the convenience valve nipple 36 preparatory to the removalof the blind end adapter bullet 130, as is necessary to restore the flowof service gas in the by-pass liner installation 40.

To remove the bullet 130 the blind end adapter tightening tool 180 shownin FIG. 10 is again made up as it is inserted through the inflation bagaperture 171 and moved down the tubing 41 into engagement with thefitting 134 at the end of the bullet 130, as indicated in FIG. 8. Thebullet is removed by pulling straight back on the tool 180 working fromthe exterior of the inflation bag 170.

As soon as the bullet 130 is pulled free from its engagement with theadapter pin 125 and its O-ring engagement within the adapter bore 111,service gas will flow from the main 20 into and through the interiorby-pass liner installation 40 to the basement tee 29, and thence up theservice riser 30 (FIG. 1). The bag 170 will, of course, inflate, showingthat the bullet has been pulled free. The rod-like shank sections 181are then disconnected as the tool 180, carrying the bullet 130, iswithdrawn from the line through the bag aperture 171.

However, before the shank section 181 which carries the bullet 130 isfinally removed from the bag 170, the convenience valve 32 is closed.The bag 170 may then be removed from the valve nipple 36, and the bullet130 removed from the bag. The closed convenience valve and itsconnection nipple 33 are then removed from the basement tee 29 and theconventional basement tee plug (not shown) is substituted, "on the fly"as is a well-known technique. The gas service system has then been fullyrestored to operation.

Thus has been described an interior by-pass liner installation,including its component elements, and techniques for making and testingit, which achieve all of the objects of the invention.

What is claimed is:
 1. A method of installing an interior by-pass linertube within a conduit comprising the steps of attaching a substantiallycylindrical adapter to, and forming a continuation of, each end of saidliner tube, each said adapter having a longitudinally spaced-apart pairof peripherally extending and exteriorly mounted radially expandablesealing gaskets thereon, inserting said liner tube within said conduitand, when each of said liner tube end adapters is in its intendedposition within said conduit, expanding said gasket pair on each adapterradially into sealing engagement with the surrounding interior surfacesof said conduit while providing a gas leakage passage having an interiorend terminus within said cylindrical adapter and an exterior endterminus on the exterior of said adapter within the region between saidpair of gaskets thereon, whereby said interior by-pass liner tube isinstalled substantially permanently within said conduit by said sealingengagement of said gasket pairs at each of its ends with said conduitinterior surfaces, and the interior of said liner tube has gas leakagecommunication with the respective interior surface portions of saidconduit and the peripheries of said gaskets between each of said gasketpairs.
 2. A method according to claim 1, wherein said conduit is a gasutility service line having a service end, and a remote end adjacent toa gas main, said installing being conducted entirely from said serviceend of said service line, and said expanding of that adapter gasket pairwhich is adjacent to said service end being performed prior to saidexpanding of that adapter gasket pair which is adjacent to said remoteend of said service line.
 3. A method according to claim 1, wherein eachof said pairs of gaskets comprises an innermost gasket and an outermostgasket with reference to said liner tube and, during said expanding ofeach of said adapter gasket pairs, said gasket of the pair which isinnermost with respect to said liner tube is substantially fullyexpanded prior to expanding the other gasket of the pair.